P0AA6 on Honda: How to Diagnose & Fix
Hybrid Battery Voltage System Isolation Fault
1 Honda model · 1 documented issue · 1 critical
P0AA6 on Honda by model: symptoms, diagnosis and fix
The hydrogen-powered 2025 CR-V e:FCEV (plug-in fuel-cell variant) was recalled because coolant can leak from the fuel cell stack coolant system into the fuel cell stack case, causing an internal short circuit between the bipolar plate and support-bar housing. This can trigger power-system, fuel-cell, and insulating-fluid warnings, drop the vehicle into a low-output mode (about 20 kW / ~27 hp), and ultimately cause a loss of drive power. Root causes were an under-validated reduction in adhesive sealant on the FC stack end joint and a supplier's missing deburring step on an O-ring groove in a coolant wobble joint. NHTSA recall 25V858000 covers 388 vehicles (nearly the entire U.S. fleet); the vehicles also fail FMVSS 305.
Common Symptoms
- Loss of drive power
- Reduced/low-output mode
- Power system warning
- Fuel cell warning
- Insulating fluid / ground fault warning
How to Fix
Under recall 25V858000, dealers replace the entire fuel cell stack assembly with redesigned seals and updated components, free of charge. Owner notification letters were expected to be mailed February 2, 2026. Affected owners should verify recall status by VIN at nhtsa.gov/recalls.
Find a Honda dealer
Choose to share your location for this search, or enter an area below. Your search location is sent to Google to find dealers.
Open Honda dealer map in Google Maps ↗Call to confirm they service Honda vehicles and check your VIN, recall eligibility, parts availability, and appointment options.
Sources for this issue (2)
P0AA6 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0AA6 mean on a Honda?
P0AA6 stands for "Hybrid Battery Voltage System Isolation Fault." P0AA6 is a hybrid/EV code meaning the battery management system detected an isolation (insulation) fault between the high-voltage battery system and the vehicle's chassis ground. For safety, the high-voltage system is normally electrically isolated from the metal body; this code sets when the measured insulation resistance drops too low, suggesting current could leak to the chassis. This is treated as a serious safety concern and often disables hybrid/EV operation or limits propulsion. The vehicle should be inspected by a qualified hybrid technician, as high-voltage components can pose a shock hazard. On Honda it is documented across 1 model: CR-V.
What are the most common causes of P0AA6?
The most common causes of P0AA6 are: Moisture or coolant intrusion inside the high-voltage battery pack, Damaged or chafed insulation on high-voltage cables, Corrosion or water in high-voltage connectors, Failed or leaking battery cell/module, Faulty inverter, converter, or A/C compressor (high-voltage components), Damaged high-voltage wiring rubbing against the chassis, Failed battery isolation/monitoring sensor. The specific cause varies by vehicle.
How much does it cost to fix P0AA6 on a Honda?
Repair costs vary widely with the root cause and Honda model; each issue on this page carries its own estimate where one is published.
Looking for P0AA6 on a different make?
View P0AA6 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.